Does Screen Time Reduce Sleep Time?

Nighttime Cell Phone Use by Students as Young as 7

Cell phone use at night may be common among children as young as 7, according to an Australian study. This practice “may not only impact negatively on sleep, but may also increase angry or hurtful communication and mental health issues,” researchers said. “On the other hand, it may also facilitate friendship building. Interventions must consider the benefits and potential losses associated with change.”

To study nighttime smartphone use by students and its associations with sleep, indicators of impaired communication, mental health, and relationship building, Jillian Dorrian, PhD, Associate Professor of Psychology at the University of South Australia in Adelaide, and colleagues analyzed data from more than 160,000 Australian students.

Primary and high school students completed an in-class survey about phone use, sleep, and friendships, as well as the General Health Questionnaire. The researchers included data from 169,352 students between ages 7 and 18 (49.9% male) in their analyses.

Fifty-five percent of respondents reported phone use between 10 PM and 6 AM at least once in the past week, including 25% of 7- and 8-year-olds and 83% of 17- and 18-year-olds.

After controlling for age and gender, nighttime phone use was associated with significantly increased odds of having responded to a text in anger (odds ratio, 4.9), having received hurtful messages (odds ratio, 4), or having been cyberbullied in the past month (odds ratio, 2.8). It also increased the likelihood of building friendships, however (odd ratio, 1.2).

In addition, nighttime phone use was associated with reduced odds of getting eight or more hours of sleep per night (odds ratio, 0.5) and less favorable General Health Questionnaire scores.

“Smartphones in the bedroom rob sleep time and facilitate communication during the circadian low,” Dr. Dorrian and colleagues said. “These factors may lead to impaired communication and disturbed mental health. However, nighttime messaging may also foster social connection…. These data highlight the ubiquity of smartphones in the bedroom, and the potential for health-related costs for developing teens, as well as a potential social cost if smartphones are removed without attention to the complete biopsychosocial context.”

—Jake Remaly